Head Banging Research
Professor Postrel called my attention to this interesting Sports Illustrated piece on efforts to measure football hits as they occur.
For years a football player taking an especially vicious hit to the head has been said to have gotten his bell rung. Like most euphemisms, that cute phrase masks a serious problem: the 300,000 sports-related concussions that take place in the U.S. every year. Medical experts still know surprisingly little about concussions, but thanks to a new device installed in football helmets at Virginia Tech, North Carolina and Oklahoma this season, researchers are beginning to amass data about these brain injuries. What they learn could force a rethinking of everything from helmet design to tackling technique and even the rules of the game.
The technology used to gather the data is called HITS, for Head Impact Telemetry System, and was developed by a team of engineers at Simbex, a Lebanon, N.H., company that specializes in biofeedback devices. HITS uses six accelerometers -- the devices that trigger auto air bags -- to measure the exact force, location and direction of each impact during a game. The accelerometers are mounted in a U-shaped pad that fits snugly into a helmet, along with a microprocessor and a radio transmitter. Each time the player's cranium accelerates due to a tackle or a collision, the acceleration is registered in g's, and that information is transmitted to a computer by the bench. There the data pops up in graphics that are easy to read even on a hectic sideline. A bar graph indicates the force of the blow, and an arrow points to the exact place of contact on a three-dimensional image of a head. If the impact exceeds a predetermined level -- it's 80 g's at Virginia Tech -- a pager instantly alerts the team doctor, who then knows to monitor the player closely.
The Hokies pioneered the use of HITS last season, rotating eight of the specially equipped helmets among 38 players. "Last year we recorded 3,312 impacts," says Stefan Duma, a mechanical engineering professor who directs Virginia Tech's Center for Injury Biomechanics. "This year, [using 20 helmets] we've recorded more than 10,000 already, with numerous concussions. This isn't the first attempt to put a monitor in a helmet. The revolutionary thing here is the magnitude of the sample and the instantaneous feedback to the team physician. What we're going to come up with is guidelines on when to look for injury."
No one knows how much force is required to produce a concussion. A five-year NFL study that used game film of concussed players to reproduce collisions using crash dummies identified 98 g's as the threshold. But this year the Oklahoma staff has recorded impacts in excess of 100 g's with no apparent consequences. In addition, the cumulative effect of subconcussive impacts, over a game and over a season, remains a mystery. Also unknown are how other factors -- such as physiology, past history, age and even altitude or air temperature -- might affect the threshold.
Alas, the link does not work for nonsubscribers. But you get the gist.